磷酸哌嗪阻燃剂的合成及其在聚氨酯注浆材料中的应用

Synthesis of piperazine phosphate flame retardant and its application in polyurethane grouting materials

聚氨酯(PU)作为注浆材料在矿井下有广泛的应用,但由于其在固化过程中放热,可能导致自燃,给井下应用带来安全隐患,因此提高聚氨酯材料的阻燃性能是非常重要的。以磷酸和无水哌嗪为原料合成了一种N-P协同型无卤阻燃剂聚磷酸哌嗪。以红外光谱和热重分析对其结构以及热性能进行表征;进一步将聚磷酸哌嗪以不同添加量对聚氨酯进行阻燃改性,研究改性后阻燃聚氨酯的各种性能。结果表明:聚磷酸哌嗪对PU具有明显的促进成炭作用。随着添加量的增加,极限氧指数(LOI)增长显著,其中PU-聚磷酸哌嗪20%的LOI值可达28.5%,UL-94的等级可达V-0级,属于难燃自熄材料,可以达到矿用注浆材料的新阻燃标准。扫描电镜测试结果表明,其燃烧后残炭表面为致密炭层,具有凝聚相阻燃特征。力学测试结果表明,随着聚磷酸哌嗪含量的增加,聚氨酯的力学性能会有所降低,但添加量为20%时,抗压强度仍然大于40MPa,满足最新安全标准要求。

Polyurethane(PU),as a grouting material,is widely used in underground mines.However,due to its heat release in the curing process,it may lead to spontaneous combustion and bring potential safety hazards to underground applications.Therefore,it is very important to improve the flame retardant performance of polyurethane materials.In this paper,piperazine polyphosphate,an N-P synergistic halogen-free flame retardant,was synthesized from phosphoric acid and anhydrous piperazine.Its structure and thermal properties were characterized by infrared spectroscopy and thermogravimetric analysis;Furthermore,the polyurethane was flame retardant modified with piperazine polyphosphate in different amounts,and various properties of the modified flame retardant polyurethane were studied.The results showed that piperazine polyphosphate could significantly promote the carbonization of PU.With the increase of the addition amount,the limit oxygen index(LOI)increased significantly.Among them,the LOI value of PU-polyphosphate piperazine 20%could reach 28.5%,and the grade of UL-94 could reach V-0,belonging to flame retardant and self-extinguishing material,which could meet the new flame retardant standard of mining grouting materials.The SEM test results revealed that the surface of the residual carbon after combustion was a dense carbon layer,which had the characteristics of condensed phase flame retardant.The mechanical test results indicated that the mechanical properties of polyurethane decreased with the increase of piperazine polyphosphate content,but when the addition amount was 20%,the compressive strength was still greater than 40 MPa,which met the requirements of the latest safety standard.